``` inline fun lt T Any R gt T notNullOrElse notNull T gt R kotlinlang #announcements

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Title

r

ribesg

03/06/2018, 8:25 AM

inline fun <T : Any?, R> T.notNullOrElse(notNull: (T) -> R, orElse: (T) -> R): R =
    if (this != null) notNull(this) else orElse(this)

val x: String? = "test"
x.notNullOrElse(
    { println(it) },
    { println("x is null") }
)

g

gildor

03/06/2018, 8:25 AM

Would be nice to add

inline

Problem with all such solutions is you need version for multiple arguments.

r

ribesg

03/06/2018, 8:27 AM

I really prefer to just define a variable and have an

if (x == null)

g

gildor

03/06/2018, 8:27 AM

yes, same for me, we don’t have such helper functions in our project

if just looks better

also there is similar case, when you want to check multiple values for null and use them only if everything is not null, you can do this using function like:

fun <A, B, C, R> ifNonNull(a: A?, b: B?, c: C?, block: (A, B, C) -> R): R?

it’s similar to applicative from functional programming

but after some concideration we decided that default constructions is enough for us, we don’t have many cases where we need it and usually you can solve it using local varialbes + early return:

val a = getA() ?: return
val b = getB() ?: "default b"
val c = getC() ?: error("c is null")
doSomething(a + b + c)

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